Telephone transmitter



Patented Apr. 12, 1927.

UNITED "STATES PATENT OFFICE}.

CHARLES-R. moons, or WYOMING, NEW JERSEY, ASSIGNOB 'ro wns'rERN ELECTRIC COMPANY, INCORPORATED, or NEW YORK, N. .Y., A CORPORATION or NEW;YOBK.

TELEPHONE TRALbTSMITTER.

This invention relates to telephonetransmitters, and the object is the-improvement of transmitters by increasing their sensitiveness, practically eliminating breathing and increasing their stability.

y In accordance with the general features of the invention there is provided a transmitter in which the chamber for the granular material. is carried by, or forms a part of, a

loosely supported system, anda barrier between the electrodes causes the concentration of current at the area of maximum agitation e of the granules. r

In accordance with another feature the di'stortive effect due to breathing, that is, the continual expanding and contracting of the various parts on. account of the continually varying temperatures caused by the cur: rent through the ranular material, is sub- 2-0 stantially reduced y loosely supporting relative to each other, the parts comprising the stem.

In its preferred form the transmitter is provided with a laminated diaphragm, each of "the outer laminations supporting at its center an annular electrode, and the intermediate lamination forming an insulating barrier between the electrodes and controlling the current path through the granular car 9 bon, a chamber for which is formed by the A disc'3, preferably of metal, has a cup shaped depression 4, the inside bottom surface of which'may be insulated by coating it-With an-insulatmg varnish or covering it with any suitable insulating material 5. Fitted into the cup and forming the elecannular electrode 6, preferably of brass lgold-plated. A disc 7 of substantially the same diameter as the disc 3 is perforated at its center and provided with an-opposit-ely extending flange 8,'within which is fitted a Second a a ele ode 9-. Bet een d c phragm 3 and the washers 17 so as to protri'cal contact with its marginal wall is an:

Application filed January 23,1923. Serial No. 614,356.

3 and 7 is disposed a third disc 10, preferably of insulating material such-as mica or phenol plastic compound. The disc 10 is provided with a central aperture having a diameter somewhat less than the inside diameter of the smaller electrode 6. Closing the opening in disc 7 is a plunger 11, the face of which is preferably coated with an, insulating compound.- Supported against the edge of the flange 8 and the electrode 9 by the plunger 11 is a plurality of loosely disposed washers 12. The space between the plunger 11 and the electrode .8, and the annular 27 on the plunger 11 is preferably more than the combined thickness of thewashers 12. The plunger 11 may be sup-' ported by any well-known means .on a bridge 13 which, in turn, is supported on an annular member 14- by means of screws 16, Between a flange 15 on the member 14 and an internal nut 20, the diaphragm 3 is loosely supported by a plurality of washers 17 of thin foil or paper disposed on each side thereof. The inside surface of the member 14 is preferably lined with insulation which may be divided into two parts 18 and 19 as shown. The space between the nut 20 and insulation 18 should be somewhat greater than the combined thicknesses of the diavide air films between adjacent washers.

Supported against the annular member 14 by means of screws 21 is the usual perforated face plate 22 carrying a mouth-piece 23.

The case 24 supports the member. 14 in any suitable manner.

.In the modification shown in Fig. 2, the

disc 7 of Fig. 1 is replaced by a disc 26 having a cup 27 similar to that of disc 3. With this form, which is suitable for inertia type transmitters, the bridge 13 and the plunger 11 of Fig. 1 are not required.

With the type of transmitter button herein disclosed, the agitation between the carbon granules and the electrodes is reduced to a minimum and confined to the region of maximum current density. By suitably proportiming the electrodes and the opening in the barrier 10, transmitters of practically any'resistancemay be obtained. Very'stable transmitters having a resistance of the order of 600 ohms may be readily provided by this structure, and are suitable for use on 48 volt 2. In a transmitter, a diaphragm com-- prising a pair of discs of substantially equal diameter, one of said discs having a central laterally extendin rim, an electrode fitted in said rim, the ot er of said discs having a central depression therein, an electrode in said depression, an insulating plate having a central aperture of less diameter thanthe inside diameter of either electrode disposed between said discs and said electrodes and a plurality of thin washers loosely; disposed at the peri hery of said dia hragm and on each side tiereof for contro ling the vibrations and supporting said discs and plate in juxtaposed relation.

3. In a transmitter, comminuted material, a diaphragm having a chamber integral therewith for said comminuted material, a I

stationary plunger forming a wall for said chamber, and a plurality of washers between said plunger and said chamber, said washers being loosely disposed so as to form air films between adjacent washers and to form a yieldable closure for holding the com; minuted material in said chamber.

d. In a transmitter comminuted material,

- a diaphragm comprising a disc having a cup-shaped central de ression therein, a second disc of substantially equal diameter having a laterally extending rim cooperating with said depression to form a chamber for said material, a plate disposed between said discs to divide said chamber into compartments and to form a restricted path through the comminuted material, and a plurality of loosely disposed washers at the periphery and at one side of each disc for securing said discs and said plate in juxtaposed relation with respect to each other. a

In witness whereof, I hereunto subscribe my name this 19th day of January A. D. 1923.

CHARLES R. MOORE. 

